INDUSTRIAL AND ENGINEERING CHEMISTRY
2584
3-METHYLPENTANE. Stock A. Distilled from hydrogenated catalytically cracked gasoline from Standard Oil Company of New Jersey (Louisiana division). After silica gel treatment, boiling range was 0.4" C., a? 1.3755, dzo 0.6619, bromine No. 0.2. Used in runs '2-530 and 553. Stock B. Phillips Petroleum Company. 1.3772, dqo 0.6638, bromine No. 0.5. Used in runs C-821 and 998. 2,3-DIhlETHYLBUT.4KE. From alkylation of isobutane with ethylene. Boiling range 56.5-57.3' C., ny 1.3732, d:" 0.6603, bromine KO. 0.3. NEOHEXANE. Stock A. From isomerization of methylpentanes with AlCla catalyst. Boiling range 48.5-48.9" C., nZ,O 1.3710, d i 0 0.6542, bromine No. 0.3. Used in run C-527. Stock B. Phillips Petroleum Company. n2$ 1.3690, d?" 0.6492. bromine h'o. 0.01. TJsed in run '2-823. OCTANE. Eastman 1Codal< Company. Roiling range 124126.2" C., nag 1.3978, d i 0 3.7025, bromine No. 0.16. ISOOCTANE. Shell Oil Company, Inc. Boiling- range - 98.699.4" C., n%?1.3925, d ? O 0.6935; bromine KO.0.04. CUMENE. Stock A. Dow Chemical Company. Boiling range 152153" C., n y 1.4912, dZo 0.8621. Used in run C-131. Stock B. Eastman Kodak Company. n9 1.4908, d:" 0.8629. Used in run C-1015 (97.7y0 cumene by infrared analysis). Stock C. From alkylation of benzene with propylene. Boiling range, 95% from 150-152.7" C., n2,0 1.4886, 0.8579, bromine KO.3.3. Used in run C-686. DECALIN.Eastman Kodak Company. Purified over silica gel. n? 1.4755, dO : 0.8837, bromine No. 0.4. 2,7-DIMETHYLOCTANE. Eastman Kodak Company. Boiling range 158-160" C., ny 1.4089, di0 0.7248, bromine No. 2.4. ~-DODECANE. From lauryl alcohol from Eastman Kodak Company. Boiling point 217" C., melting point -9.8" C., nSo 1.4216, dO : 0.7486. ISODODECANE. Hydrogenated triisobutenes from Shell Oil Company, Inc. from cold acid polymerization of isobutene. A.S.T.M. 5% and 95y0 distillation temperatures were 175.8' and 178.7"C., n2$ 1.4201, dO : 0.7474, bromine No. 3.9. CETENE. N. V. de Bataafsche Pet,roleum Mij., Delft, Holland. Stock A. Melting point 4.05" C., n'g 1.4409, d i o 0.7813, bromine KO.69.3. Used in run C-46. Stock B. Melting point 3.6" C., n y 1.4398, dqo 0.7822, bromine No. 68.5. Used in run C-721. CETANE. E. I. du Pont de Nemours & Company, Inc. Several lots of similar properties were used. Range of properties: melting point _16.7-17.0" C., ng 1.4345-1.4348, di0 0.7726-0.7742, bromine no. 0.2-0.3. BORNEO Wax. Kestern Waxed Paper Company, Emeryville, Calif. nY 1.4356, d:" 0.7786, melting point 53.4" C., molecular weight 368.
Brunauer, S., Emmett, P. H., and Teller, E., Z b i d . , 60, 309 (1938). Dobryanskii, A . F., Kanep, E. K., and Katsman, S. V., Trans. Reaearch Plant Khimgaz, 3, 1 (1936). Evans, A . G., and Polanyi, M., J . Chem. Soc., 1947, p. 252. Frost, A . V., J . Phgs. Chem. (U.S.S.R.), 14, N o . 9/10, 1313-18 (1940). Gault, H., and Altchidjian, Y., Ann. chim., (10) 2, 209 (1924). Good, G. M . , Voge, H. H., and Greensfelder, B. S.,IND.ENG. C H E M .39, , 1032 (1947). Greensfelder, B. S., and Voge, H. H., Ibid., 37, 514 (1945). Ibid., p. 983. Ibid., p. 1038. Greensfelder, B. S., Voge, H . H., and Good, G. M . , I h i d . , p. 1168. Hansford, R. C., Ibid., 39, 849 (1947). Henriques, H. J., Ibid., p, 1564. Hipple, J. A . , and Stevenson, D. P., J . Am. Chem. SOC., 64, 1590, 2766, 2769 (1942). Ingold, C. K., Raisin, C. G., and Wilson, C. L., Nature, 134, 847 (1934) ; J . Chem. Soc., 1936, pp. 915, 1643. Kasanskii. B. A., and Plate, A . F., Ber., 67, 1023 (1934). Kossiakoff, A , and Rice, F. O., J . Am. Chem. SOC.,65, 590 (1943). Marisic, M. M. (to Socony-Vacuum Oil C o . ) ,U. S.Patent 2,394,796 (1946). Oblad, A. G., and Gorin, hf. H., ISD. ESG. C H E M . ,38, 822 (1946). Pauling, Linus, "The Nat,ure of the Chemical Bond," 2nd ed., Ithaca, N. Y . ,Cornell University Press, 1940. Peski, A. 3. van (to Shell Development C o . ) , U. S. Patent 2,172,228 (1938). Pines, H., and Wackher, R. C., J. Am. Chem. SOC.,68, 595
nso
LITERATURE CITED
(1) Bartlett, P. D., Condon, F. E., and SchneideI, A , J. Am. Chem. Soc., 66, 1531 (1944). ( 2 ) Bawn, C . E. H., Trans. Faraday Soc., 34, 598 (1938). (3) Bloch, H. S., Pines, H., and Schmerling, L., J . Am. Chem. Soc.,
68, 153 (1946).
Vapor pressure of Maleic
Vol. 41, No. 11
(1946).
Rice, F. O., Ibid., 55, 3035 (1933). Rice, F. O., and Rice, K. K., "The Aliphatic Free Radicals," Baltimore, Johns Hopkins Press, 1938. Rice, F. O., and Teller, E., J. Chem. Phys., 6 , 489 (1938); 7, 199 (1939). Roberts, R. M,, Shell Development Company, Emeryville, Calif., unpublished work. Shell Development Company, Emeryville, unpublished work. Sundgren, A , , Ann. ofice natl. combustibles liquides, 5,35 (1930). Tamele, M. W., and co-workers, Shell Development Company, Emeryville, unpublished work. Thomas, C. L., IND.ENQ.CHEM.,41, 2564 (1949). Voge, H. H., and Good, G. M., J. Am. Chem. Soc., 71, 593 (1949). Voge, H. H., Good, G. AM.,and Greensfelder, B. S., IND.ENG. CHEM.,38, 1033 (1946) Wheland, G. W., "The Theory of Resonance," pp. 233--4, New York. John Wilev & Sons. 1944. Whitmore, F. C., Chem. knp. News,26, 668 (1948). Whitmore, F. C., IND.ENG.CHEM.,26, 94 (1934). Whitmore, F. C., J . Am. Chem. Soc., 54, 3274 (1932). Whitmore, F. C . , and Stahly, E. E., Ibid., 55, 4153 (1933). I
(36) (37) (38)
(39)
RECEIYED August 2 , 1948.
LEON 0. WINSTROM AND LAURENCE KULP' Allied Chemical and Dye Corporation, New York, N . y .
~
TEMPERATURE RANGE FROM 35" TO 77" C.
T h e vapor pressure of maleic anhydride has been measured in the temperature range from 35" to 77" C. A new static method for the measurement of the vapor pressure of sublimable substances is described.
URIKG the course of process development in expanding the production of maleic anhydride (Toxilic anhydride), it became necessary t o know the vapor pressure of this substance a t temperatures near its melting point. The only data available in the literature are those tabulated in Landolt-Bornstein (4) which refer to unpublished data obtained from I. G. Farben. Weiss and Down8 (6) determined this property a t higher teniperatures but they give only one value in the range of interest,. 1
Present address, Coliimbia University, New York 27, S . Y .
November 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
I n view of the questionable reliability of unpublished measurements, the desired data were determined in this laboratory. MATERIALS
MALEIC ANHYDRIDE.This is produced by the National Aniline Division of Allied Chemical & Dye Corporation. The sample used had an original solidification point of 52.7" C. and a molten color of No. 10 on the Co-Pt (Hazen) scale. It was further purified by hydrating with distilled water to form maleic acid and twice recrystallizing this from distilled water before
2585
from the balancing nitrogen pressure. Figure 1 is a diagram of the apparatus, Its essential features are as follows: A 1-liter flask, A , is enclosed in thermostat B, which is regulated to within *O.l " C. The flask is connected to the nitrogen system by a 0.5-mm. capillary tube 10 om. long closed by stopcock z,and to a high vacuum system by stopcock 5,. C is a sublimate trap immersed in ice bath D to prevent sublimed vapors from entering the McLeod gage system. E is a 2-liter ballast flask to permit easy regulation of the nitrogen pressure. F is a McLeod gage. 2 2 is a stopcock leading to the high vacuum side of a mercury
SYSTEM
S'
X
Figure 1. Vapor Pressure Apparatus
drying the crystals in vacuo a t 60" C. The dry acid was djstilled under 150 mm. pressure; this formed the anhydride, which was separated from the water by condensation. The anhydride so obtained was twice fractionated over phosphorus pentoxide a t 50 mm. pressure, using a 24inch Wjdmer column. The middle third fraction was preserved in each distillation. The final product solidified at 52.8' C. and had a color of zero on the Co-Pt scale; this attested to the high purity of the original commercia1 product. RESUBLIMED NAPHTHALENE. This was obtained from the Barrett Division of Allied Chemical & Dye Corporation. It was twice recrystallized from absolute alcohol, and the crystals were vacuum-drjed. The h a 1 product solidified a t 80.2"C. KITROGEN.The material used in these experiments was obtained from the Linde Air Products Company. It was purified by passing it over heated, metallic copper and then dried by bubbling it through concentiated sulfuric acid before conducting it through a drying tower filled with phosphorus pentoxide. APPARATUS AND PROCEDURE
Because maleic anhydride has a tendency to sublime a t ordinary temperatures, the measurements were made by a new, static method developed in this laboratory. In this method, pure dry nitrogen is used to balance the vapor pressure of thasubstanoe under investigation. The nitrogen pressure is measured by means of a McLeod gage, and the vapor pressure is read directly
diffusion pump. zs is a notched stopcock leading to a nitrogen purification train. Prior to insertion of the sample, flask A was cleaned with sodium dichromate solution, hydrochloric acid, and distilled water, in the order named, and then thoroughly flamed while connected t o the high vacuum system. It was allowed to cool under vacuum and was then filled with nitrogen. The large neck of the flask was broken, the substance whose vapor pressure was to be measured was inserted, and the neck was resealed. The flask was then immersed in an ice bath and evacuated t o less than 0.0075 mm. pressure. The stopcocks were closed, and the evacuated flask was placed in the thermostat and sealed into the system a t s and s'. Flask A is held a t the desired temperature in the thermostat until temperature equilibrium is attained. Ice is placed in ice trap D,and stopcock zzis opened. All other stopcocks are closed. After the system is evacuated to the limit of the high vacuum system, stopcock z~is closed. Nitrogen is now slowly admitted through z p or withdrawn through 52 until the nitrogen pressure in E', F, and C reaches a value somewhat below the estimated vapor pressure in A . Stopcock z is now opened for about 10 seconds; after it is closed, a new reading is taken on the McLeod gage. If the nitrogen pressure is really less than the vapor pressure, a white mist of vapor will be noticed rising to stopcock 2. The emergent vapors will compress the nitrogen in the tube z-s, and the second reading on the McLeod gage will be higher than the first.
INDUSTRIAL AND ENGINEERING CHEMISTRY
2586
z2is now opened. Tube z-8 is heated with an infrared lamp, which drives the condensed vapors into ice trap C where thejr pressure (maleic anhydride) is Iess than 0.01 mm. Tube z-s is allowed to cool, and the nitrogen pressure in the measuring system is readjusted to the value obtained after compression in the first trial. Stopcock x is again opened for 10 seconds; after it is closed, another reading is taken on the McLeod gage. The trial balancings are repeated until, at some pressure, no change is observed in the readings before and after opening stopcock z. This is the observed vapor pressure. Increasing the nitrogen pressure slightly above this pressure results in the second nitrogen pressure determination being lower than the first.
Vol. 41, No. 1 1
TABLE I. VAPORPRESSURE OF NAPHTHALENE (MM.) Temp.,
C.
30 40 50
60
Allen 0.14 0.32 0.81 1.83
Av. Barker Thomas Andrews Other 0.16 0.13 0.12 0.14 0.39 0.33 0.30 0.34 0.88 0.81 0.76 0.82 1.88 1.82 1.83 1.84
This Deviation Method from Av. 0.12 -0.02 0.33 -0.01 0.82 0.00 1.86 $0.02
TABLE 11. VAPORPRESSURE OF MALEICANHYDRIDE Temp., C. 35.0 40.0
Mm. H g 0.36 0.69 1.22 1.90
45.0
50.0 51.0
1.99
52.0
2.16 2.24 2.34 2.53 3.30 4.43 5.93 8.01 9.04
52.W 54.0 55.0
60.0
65.0 70.0 75.0 77.0 Melting point.
9,0
control than was given by the thermostat used. The results obtained with naphthalene demonstrate the applicability of the method to maleic anhydride. The results on this compound are given in Table 11. These data, together with the values of Landolt-Bornstein and Weiss and Downs, are plotted in Figure 2 , DISCUSSION
I
r.o,L--
30
Figure 2.
T-
40
50
60
TEMPERATURE,
C.
10
EO
Vapor Pressure of Maleic Anhydride 0 Authore' data X Weise and Downs, experimental A Weiss and Downs, calculated
Although results on duplicate samples checked to within 0.02 mm., even a t the upper limit of the pressures measured, it seems probable that the absolute limit of accuracy would not be closer than 0.05 mm. because of the limits of temperature control used. Aside from errors due to temperature control, the accuracy of the method is limited only by the gaseous diffusion. However, the capillary chosen (0.5 mm.) was of a size calculated to keep diffusion errors well within the limit of accuracy of the determinations. As can be seen from Figure 2, Weiss and Downs' experimental value a t 72' C. agrees well with the data obtained here. Their calculated value together with the Landolt-Bornstein data falls slightly above the present measurements in the liquid phase. A simple calculation from the Clapeyron equation gives the heat of vaporization of maleic anhydride (calculated from 52.8" to 77.0" C.) as 13.1 kg.-cal. per mole.
I. G. Farbenindustrie data
ACKNOWLEDGMENT
After each determination of the equilibrium nitrogen pressure, flask A is chilled to 0 " C. and re-evacuated to remove nitrogen admitted in the h a 1 balance check. Recorded measurements are made with a t least two samples, and each sample is checked by at leaqt three halancings in rompiling the final determination. RESULTS
In order to test the method, the vapor pressure o f naphthalene was measured a t temperatures of 30 O , 40 O , 50 ', and 60 O C. Each recorded measurement was made with a least two samples of naphthalene, and each sample was checked by a t least three balancings in compiling the final determination. The values determined are compared with those of Allen ( I ) , Barker (S), Thomas ( 5 ) , and Andrews (g) in Table I. The maximum deviation from the average of individual readings on a given sample a t a given t,emperature was 0.01 mm. Duplicate samples checked within the same limits of accuracy. More accurate determinations would require closer temperature
The authors wish t o express their appreciation t o E. B. Punnett for his contributions to this investigation. LITERATURE CITED
(1) Allen, R. W., J. Chem. Soc., 7 7 , 410 (1900). (2) Andrews, M. R., J . Phys. Chem., 30, 1947 (1926). (3) Barker, J. T., 2. phusik. Chem., 71, 235 (1910).
Landolt-Bornstein, "Physikalish-Chemische Tabellen," Vol. 2, Supl. 2 , p. 1308, Berlin, Julius Springer, 1931. (5) Thomas, J. S. G., J . Soc. Chem. Ind.,35, 506-13 (1916). (6) Weiss, J. M.,and Downs, C. R., J . Am. Chem. SOC.,43, 1004 (4)
(1923). RBCEIVED April 4, 1949.
